Stochastic estimation and flow sources associated with surface pressure events in a turbulent boundary layer

The ability of stochastic estimation to capture the conditional streamwise velocity field associated with wall-pressure events was investigated using simultaneous hot-wire and microphone measurements over the Reynolds number range: 1437 less than or equal to Re(theta)less than or equal to 5670. The velocity measurements were conducted at the same streamwise and spanwise lo cation as the wall-mounted microphone but at various heights in the boundar y layer, spanning the buffer and logarithmic regions. The results show that utilization of the wall-pressure as the event for the stochastic estimatio n requires the inclusion of both the linear and quadratic terms in order to provide an accurate representation of the conditional velocity field. The need for the inclusion of the quadratic term, which is unlike published res ults based on velocity and Reynolds stress events in wall-bounded flows, is attributed to the influences of the turbulent-turbulent pressure source te rm. Additionally, examination of the energy content of the quadratic compon ent of the stochastic estimation and its Reynolds number scaling suggests t hat the quadratic term is associated with motions that scale with the bound ary layer thickness. (C) 2001 American Institute of Physics.